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Feeding power to the garage down the garden

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sowen Club Retro Rides Member Posts: 2,245 Club RR Member Number: 24	Feeding power to the garage down the garden sowen @sowen Club Retro Rides Member 24
	Jun 2, 2023 18:08:02 GMT Select Post Deselect Post Link to Post Back to Top
	I moved into my new home a few months back with ample room for all my toys and projects. There's a garage and a substantial shed down my garden away from the house. We're told the previous owners had electricity running to them which was rightly condemned and mostly removed. The house is a bit of a project so I've had the electricians in doing some re-wiring inside, and whilst they were at it I had them install a 50amp supply to the back of the house to power the garage. My question is what is the best recommeded way to get the electricity from the house to the garage? I'm assuming I'll be digging a trench and dropping armoured cable into it. How deep should I be going and should I have the cable inside some sort of sealed conduit? I also want running water, washing hands and filling the kettle. Should any water pipes go in a seperate conduit? Should I put something down to protect the water and electricity under the ground? Years ago when my parents had their house extended and built the garage they had a 6" plastic tube joining the house to garage buried under a small walkway with both electricity cables and water pipe inside, though the water was never turned on from the house.
	'72 Rover P6 2300TC Saab turbo '75 Land Rover SIII swb '84 Rover SD1 3500 Vitesse '71 Rover P6 Ratty OM606 Landy

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homersimpson Posted a lot Posts: 1,239	Feeding power to the garage down the garden homersimpson @homersimpson
	Jun 2, 2023 18:48:16 GMT Select Post Deselect Post Link to Post Back to Top
	The cable to the garage needs to be steel wire armoured (SWA) to provide it with mechanical protection. Unless you ever think you might need to upgrade it then burying it direct in the ground is fine. It should be at least 300mm deep, more if there is any risk of it being dug up when gardening. The water pipe needs to be at least 600m down to prevent it freezing in the winter. They can be together in the same trench with a small (say 150mm) gap between them, I would also put some marker tape over them at about half their depth to warn anyone in future of their presence.


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jimi Club Retro Rides Member Posts: 2,252	Feeding power to the garage down the garden jimi @jimil
	Jun 2, 2023 21:56:14 GMT Select Post Deselect Post Link to Post Back to Top
	IIRC unless the Regs have changed, it has to be a metal sheathed cable i.e SWA [Single Wire Armoured], DWA [Double Wire Armoured] or MICC [Mineral Insulated Copper Sheathed] any other type cable has to be in metal conduit. Cable should be at least 18" (457mm) deep and buried with a warning tape on top of it.
	Last Edit: Jun 2, 2023 22:09:56 GMT by jimi Black is not a colour ! .... Its the absence of colour

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chandlergti Club Retro Rides Member Posts: 1,253	Feeding power to the garage down the garden chandlergti @chandlergti
	Jun 2, 2023 22:30:29 GMT Select Post Deselect Post Link to Post Back to Top
	Jun 2, 2023 21:56:14 GMT jimi said: IIRC unless the Regs have changed, it has to be a metal sheathed cable i.e SWA [Single Wire Armoured], DWA [Double Wire Armoured] or MICC [Mineral Insulated Copper Sheathed] any other type cable has to be in metal conduit. Cable should be at least 18" (457mm) deep and buried with a warning tape on top of it. So you can’t have a plastic conduit bored under ground? Why would you want metal in a moist location at all? I had a line borer stop by and thread some 1.5” nylon conduit from house to barn last year. Was reasonable.
	Last Edit: Jun 2, 2023 22:32:29 GMT by chandlergti

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jimi Club Retro Rides Member Posts: 2,252	Feeding power to the garage down the garden jimi @jimil
	Jun 3, 2023 1:48:53 GMT Select Post Deselect Post Link to Post Back to Top
	I don't have a copy of the current regulations (18th edition) so I looked it up in the copy I have (16th) and it doesn't specifically say metal conduit, only that the conduit must supply the same degree of mechanical protection as armoured cable. It's under Special Installations 7.13.3 - Underground wiring Three types of cable may be installed underground: 1. - armoured or metal sheathed or both 2. - p.v.c. insulated concentric type. Such a cable will have the neutral (and possibly the protective conductor) surrounding the phase conductor. An example is shown in {Fig 4.1(c)}. 3. - Any suitable cable enclosed in conduit or duct which gives at least the same degree of mechanical protection as an armoured cable. No specific requirements for depth of burial are given in the Regulations, except that the depth should be sufficient to prevent any disturbance of the ground reasonably likely to occur during normal use of the premises. Hence, a cable to outbuildings installed under a concrete path could be at 400 mm, whilst if running through a cultivated space which could be subject to double digging would be less likely to disturbance if buried at 700 mm. For caravan pitches, cables should be installed outside the area of the pitch, unless suitably protected, to avoid damage by tent pegs or ground anchors. Cables must be identified by suitable tape or markers above the cable, so that anyone digging will become aware of the presence of the cable. Cable covers may also offer both identification and protection as shown in {Fig 7.22}. It is often useful to lay a yellow cable marker tape just below ground level so that this will be exposed by digging before the cable is reached. Careful drawings should also be made to indicate the exact location of buried cables; such drawings will form part of the installation manual (see {8.2.1}).
	Last Edit: Jun 3, 2023 1:56:10 GMT by jimi Black is not a colour ! .... Its the absence of colour

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chandlergti Club Retro Rides Member Posts: 1,253	Feeding power to the garage down the garden chandlergti @chandlergti
	Jun 3, 2023 1:56:03 GMT Select Post Deselect Post Link to Post Back to Top
	Ah, that’s good then. Flexible PVC is ok


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jimi Club Retro Rides Member Posts: 2,252	Feeding power to the garage down the garden jimi @jimil
	Jun 3, 2023 1:58:51 GMT Select Post Deselect Post Link to Post Back to Top
	Just edited my reply for clarity. If it's concentric cable it's OK
	Black is not a colour ! .... Its the absence of colour

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sowen Club Retro Rides Member Posts: 2,245 Club RR Member Number: 24	Feeding power to the garage down the garden sowen @sowen Club Retro Rides Member 24
	Jun 3, 2023 8:39:20 GMT Select Post Deselect Post Link to Post Back to Top
	Excellent stuff thankyou all. We use the area between the house and garage for car parking, and the previous occupants appear to have had the entire area behind the house two car lengths deep covered in awful tarmac over mud! Exploratory holes have gone through it easily enough with a hammer, chisel and crowbar. I should be able to dig a deep enough trench through that to the garage. The novelty of a tarmaced area behind the house wore off quick with the quantity of small stone being walked into the house. There's a concrete path running to the bottom of the garden so I can easily follow that to the bottom when I begin the new workshop build. That leaves how to get a cable from in the bottom of a trench outside to being joined to the cable ready in my kitchen. Run the conduit up the wall and put a junction box inside?
	'72 Rover P6 2300TC Saab turbo '75 Land Rover SIII swb '84 Rover SD1 3500 Vitesse '71 Rover P6 Ratty OM606 Landy

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homersimpson Posted a lot Posts: 1,239	Feeding power to the garage down the garden homersimpson @homersimpson
	Jun 3, 2023 17:44:03 GMT Select Post Deselect Post Link to Post Back to Top
	Jun 2, 2023 22:30:29 GMT chandlergti said: Jun 2, 2023 21:56:14 GMT jimi said: IIRC unless the Regs have changed, it has to be a metal sheathed cable i.e SWA [Single Wire Armoured], DWA [Double Wire Armoured] or MICC [Mineral Insulated Copper Sheathed] any other type cable has to be in metal conduit. Cable should be at least 18" (457mm) deep and buried with a warning tape on top of it. So you can’t have a plastic conduit bored under ground? Why would you want metal in a moist location at all? I had a line borer stop by and thread some 1.5” nylon conduit from house to barn last year. Was reasonable. With SWA and concentric cable the outer metalic protection is covered in a plastic sheath and hence is completely isolated from any water ingress. In 25 years in the electrical industry i've only ever seen one issue with a buried underground SWA cable suffering water ingress and that was due to the failure of resin joint that had been put into the cable.


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kevins Posted a lot Posts: 4,862	Feeding power to the garage down the garden kevins @kevins
	Jun 5, 2023 11:40:36 GMT Select Post Deselect Post Link to Post Back to Top
	I believe you can take SWA above ground along a fence or wall as long as it's clipped away from where it could be damaged or cause a trip hazard.


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homersimpson Posted a lot Posts: 1,239	Feeding power to the garage down the garden homersimpson @homersimpson
	Jun 5, 2023 19:59:05 GMT Select Post Deselect Post Link to Post Back to Top
	Jun 5, 2023 11:40:36 GMT kevins said: I believe you can take SWA above ground along a fence or wall as long as it's clipped away from where it could be damaged or cause a trip hazard. Absolutley, you can clip it direct to any surface that it can get a good strong fixing to, I worked on one job where we fixed them to the fence about 300mm off the ground so that the volunteers who worked at the centre wouldn't damage them while tending the planting borders. The idea with the armouring is that not only does it provide mechanical protection but also its earthed and so if you go through the cable accidentally the short circuit occurs between the live conductor and earth and the effect on the person is reduced (althought likely still deadly) and the protection (fuse/circuit breaker) clears more quickly because of the higher fault current that flows.


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squonk Part of things Posts: 864	Feeding power to the garage down the garden squonk @squonk
	Jun 20, 2023 9:51:10 GMT Select Post Deselect Post Link to Post Back to Top
	Correct me if I'm wrong but my understanding (from a professional electrician friend) is that as this is effectively a new wiring installation (the old one having been removed) installing a mains supply to an external building is classified as Notifiable under Part P of the building regulations. It either has to be done by a person who has Part P qualifications or certified by a Part P qualified person. If not done this way your local authority can order you to remove the installation. You may also find that if you do it yourself and don't get it certified it may invalidate your house insurance. Of course, thats if anyone were to find out!!!!
	2004 Chevrolet Avalanche Z71 2005 Mercedes CLK320 Cabriolet 1996 Mercedes C180 Elegance Auto Saloon 1996 Rover 620Ti (Dead fuel pump) 1992 Toyota HiLux Surf 1987 Range Rover Vogue (Rusty) 1992 Range Rover Vogue SE (More Rusty) 2006 Chrysler Grand Voyager 2008 Corsa 1.4 Design

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kevins Posted a lot Posts: 4,862	Feeding power to the garage down the garden kevins @kevins
	Jun 20, 2023 12:37:16 GMT Select Post Deselect Post Link to Post Back to Top
	The last part is the key part, if you do it right nobody is ever likely to notice or find out, if you do it wrong potentially all sorts of horrors. Bottom line - unless you are very confident in what you are doing get it checked out. You can save a lot of money by doing the donkey work yourself (digging trenches, channelling conduit and back boxes in etc) then pay the pro to wire it up.


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jamesd1972 Club Retro Rides Member Posts: 2,922 Club RR Member Number: 40	Feeding power to the garage down the garden jamesd1972 @jamesd1972 Club Retro Rides Member 40
	Jun 20, 2023 15:22:13 GMT Select Post Deselect Post Link to Post Back to Top
	Got various bits of SWA all over the place here some buried, some clipped to walls etc. all more or less to the regs (date dependent). Some thoughts to share in case they help: Going up or along a wall on clips doesn't look too bad but get the clip spacing even and level or it will drive you nuts. SWA can be 2 core using the outer as an earth or 3 core. 3 core easier to wire up but more expensive. Doing the end glands well is difficult even for those with experience so get the pro to do this bit. If any trees en-route try and avoid chopping roots too much, they don't like it and can easily kill the tree. When filling back in leave at least 3" proud as the trench will drop over time. Hope this helps the thought process - sound like a nice project you have. James
	Last Edit: Jun 20, 2023 15:22:38 GMT by jamesd1972

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sowen Club Retro Rides Member Posts: 2,245 Club RR Member Number: 24	Feeding power to the garage down the garden sowen @sowen Club Retro Rides Member 24
	Jun 20, 2023 20:21:19 GMT Select Post Deselect Post Link to Post Back to Top
	The electrician has laid the wiring from the breaker box at the front of the house through to the back, but not connected it in the box. When the time comes they'll come back to connect it all up and make it live. They did suggest we contact our electricity supplier to have the house supply breaker upgraded from 60amp to 100amp to reflect the potential new loads. I've done some work in the back parking area and found the tarmac to be of exceptionally poor quality so digging a trench through that won't pose much of a problem. From there there's a concrete path that goes beside the garage to the bottom of the property where I plan to build the new workshop/garage. Running a trench alongside that would work well for my requirements. All subject to the electricians accepting my plans. Budget has been hit really hard recently so I may just dismantle the existing prefab garage and reconstruct it at the bottom with some alterations to suit my needs....
	'72 Rover P6 2300TC Saab turbo '75 Land Rover SIII swb '84 Rover SD1 3500 Vitesse '71 Rover P6 Ratty OM606 Landy

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v8ian Posted a lot Posts: 3,832	Feeding power to the garage down the garden v8ian @v8ian
	Jun 20, 2023 20:35:31 GMT Select Post Deselect Post Link to Post Back to Top
	Another option run power up a garden or across to a shed is suspend it in the air from a wire, and clip/cabletie a external grade cable (dosent need to be armoured), I have on several occasions run power to sheds this way,Eyebolts on each building, string a wire between and twist tight, clip the cable to this, and before you enter the cable into the building put a loop in the cable to prevent water running into the building, Perfectly legal in the 17th, don't know about the 18th
	Last Edit: Jun 20, 2023 20:36:51 GMT by v8ian Atmo V8 Power . No slicks , No gas + No bits missing . Doing it in style. Austin A35van, very different------- but still doing it in style, going to be a funmoble

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